Hi, long time listener, first time caller . . .
I've come to this forum many times over the past few years during the process of building my natural swimming pond (above). So many talented and visionaries here on this forum. I learned a heap building it and made lots of mistakes. Probably the biggest blunder was adding pea gravel in the bottom of the pond. I did a metric shite ton of research and came across to different schools of thoughts regarding pea gravel in a pond. I decided to go this route and did so for a couple of reasons - keep it "natural" looking and making it easy on the feet when swimming.
HOWEVER, pea gravel in a pond where no little feet will be stirring up the detritis and dirt caught in it over two years really did a job on the water quality. I got a late start on my pond this spring due to a shoulder injury and cold, wet weather. I decided to remove the pea gravel and find another solution for the bottom.
A little about my pond . . . .it is roughly 35' long x 15' wide (not counting the planted regeneration zones) x 6.5' deep (in the deepest section). I have a skimmer/mechanical filter with a submerged pump that sends the water through a UV sterilizer, then onto the water fall which contains some bioballs in it's weir. I have a 12" air diffuser in the deep end which pushes water upward while at the same time adding oxygen. I am in the process of building two 55 gal drum fines filters as well which will come before the UV. I used David Pagean Buttler's air lift system for the plant zones. I keep no fish. In the summer we share the swimming with a frog or two.
Water drained - don't use pea gravel in the bottom of a natural swimming pond. It gets really gross. I had bought a very good pond vacuum toward the end of last season but it was very difficult to vacuum the dirt from the bottom as it was mixed into the pea gravel (which was 2"- 3" deep). The vacuum sucked up gravel and cause the vacuum to work too hard.
Pea gravel being vacuumed out. I would have shovelled it by hand but my shoulder was buggered up. The industrial vacuum truck had it empty in under two hours!
Pressure washed after pea gravel was removed. Really hard to get the red "stuff" off. It appeared to me to be mineral deposit from the pea gravel? It is like it is imbedded into the EPDM - it's not slimy or organic. I had a layer of geo-textile between the EPDM and the pea gravel.
Sooooo. Now what? My initial thoughts were to pour a concrete bottom so that I'd have a smooth surface to vacuum, stay ahead of the build up of dirt and keep the water quality in check. BUT, that's going to be very expensive (truck delivering and pumping concrete in - $$$). So my next thought was adding a regular pool liner - blue in colour (my two girls weren't crazy about having a dark bottom despite the water quality being very good). I figured I would only go up as high as the cedar wood with the blue pool liner. The only trouble would be the liner, once in place and water added would float up the minute water got between it and the EPDM.
Would gluing the pool liner to the EPDM work? If so, what kind of glue would work? Dab or dots of glue randomly spread about or using a foam roller (like painting)?
Any other ideas would be greatly appreciated.
I'd suggest having a trench at the lowest points in tge pond.. with a perforated pipe in the trench with a clean out access. I'll be doing this and using my vacuum to sick out the clean out lines. I too am using a blue liner in my deep end and only have rock in my regenerate zones. No rock bottoms so I can use a vacuum as needed. But an shelves or regeneration zones will have trenches for heavy debris settlement and just clean them as needed. I'd suggest watch the English version of the Swim Teich pools YouTube channel. Smooth out your bottom before you put in the liner. How you shape the bottom and how smooth it is will determine how easy it is to clean after you put the liner down. You can try using air at the bottom too and get things moving around. Try having a return at the bottom of the pond and pump ur return line to the deep end. I'd suggest a retrofit bottom drain, and a return. If you want to keep the black liner there's printed thin liner you could put in the bottom that looks like pebbles but us a liner. Weight it down with grace bags or pavers. Put some lights down there too. There's shapes you can make in the bottom that helps the debris settle at the lowest point and all you have to do is brush the sides let it settle for a day then vacuum out the lowest points.
